Buying businesses for meaningfully less than what they are intrinsically worth, then letting the market's mood swings work in your favor.
Ben Graham's core idea: treat the stock market as a business partner named Mr. Market who shows up daily offering to buy or sell at wildly different prices depending on his mood. You are never obligated to trade with him — only to use his quotes when they serve you, and to buy only when the price sits well below your honest estimate of the business's worth.
Every day the market offers a price. That price is a mood, not a verdict — it swings with fear and euphoria, not with the business's actual worth.
Independently of the quote, estimate what the business is actually worth — conservatively, based on durable cash-generating power, not this quarter's headline.
Act only when price sits well below value — the gap is your cushion against bad luck, bad timing, and your own errors of judgment.
Buffett's earliest partnership years leaned on classic Graham-style bargains — statistically cheap, often mediocre businesses bought for less than their liquidation value, good for one last "free puff" of profit before being sold.
Munger pushed Buffett to pay a price above net asset value for See's Candies because its brand and pricing power made it worth far more than its balance sheet suggested — the moment value investing evolved from cheapness alone to quality plus a fair price.
Berkshire bought its stake during a market downturn at a price far below Graham-style estimates of the company's intrinsic worth, then held for decades as the underlying business compounded — a textbook margin-of-safety purchase.
Estimate intrinsic value from durable owner earnings and cash-generating power, not accounting profit alone.
Build in a real margin of safety — don't buy at a price that only works if your estimate is exactly right.
Treat daily price quotes as an option to trade, never as a scoreboard on the business's true worth.
Separate the price you pay from the value you receive — they are related but rarely equal.
Favor quality and durability over pure statistical cheapness once you can afford to pay up slightly.
Be patient — Mr. Market's pessimism, not his optimism, is when the discipline pays off.
The core idea Munger returned to again and again: it is far better to buy a wonderful business at a fair price than a fair business at a wonderful price.